47.对文件中的结构体数组进行排序

程序通过定义学生结构体变量，存储了学生的学号、姓名和3门课的成绩，所有学生数据均以二进制方式输出到文件中。函数fun的功能是从形参filename所指的文件中读取学生数据，并按照学号从小到大排序后，再用二进制方式白排序后的学生数据输出到filename所指的文件中覆盖原来的内容。

#include<stdio.h>
#define N 5
typedef struct student
{
long  sno;
char name[10];
float score[3];

}STU;
void fun(char *filename)
{
errno_t err;
FILE * fp;
int i, j;
STU s
, t;
err = fopen_s(&fp,filename,"rb");
fread(s, sizeof(STU), N, fp);
fclose(fp);
for (i = 0;i < N - 1;i++)
for (j = i + 1;j < N;j++)
if (s[i].sno>s[j].sno)
{
t = s[i];
s[i] = s[j];
s[j] = t;

}
err = fopen_s(&fp,filename, "wb");
fwrite(s, sizeof(STU), N, fp);
fclose(fp);

}

int main()
{
errno_t err;
STU t
= { {10005,"Zhangsan",95,80,88},{10003,"LiSi",85,70,78},{10002,"CaoKai",75,60,88},{10004,"FangFang",90,82,87},{10001,"MaChao",91,92,77} }, ss
;
int i, j;
FILE * fp;
err = fopen_s(&fp,"student.dat","wb");
fwrite(t, sizeof(STU), N, fp);
fclose(fp);
printf("\n\nThe original data:\n\n");
for (j = 0;j < N;j++)
{
printf("\nNo;%ld Name:%-8s Score:", t[j].sno, t[j].name);
for (i = 0;i < 3;i++)

printf("%6.2f", t[j].score[i]);
printf("\n");

}
fun("student.dat");
printf("\n\nThe data after sorting:\n\n");
err= fopen_s(&fp,"student.dat", "rb");
printf("%d", err);
fread(ss, sizeof(STU), 5, fp);
fclose(fp);
for (j = 0;j < 5;j++)
{
printf("\nNo:%ld Name:%-8s Score:", ss[j].sno, ss[j].name);
for (i = 0;i < 3;i++)
printf("%6.2f", ss[j].score[i]);
printf("\n");

}
getchar();
return 0;

}